Light fixture with spring toggle diffuser retention means



June 27, 1967 F. L. GREEN 3,328,579

LIGHT FIXTURE WITH SPRING TOGGLE DIFFUSER RETENTION MEANS Filed Aug. 24,1964 2 Sheets-Sheet l IN VEN'TOR. Fmm/c [5 6REEN ATTORNEYQ June 27, 1967F. GREEN LIGHT FIXTURE WITH SPRING TOGGLE DIFFUSER RETENTION MEANS FiledAug. 24, 1964 2 Sheets-Sheet 2 l N VEN TOR. [RIDER/c [5E GREEN ATTORNEYSUnited States Patent 3,328,579 LIGHT FIXTURE WITH SPRING TOGGLE DIFFUSERRETENTION MEANS Frederic Lee Green, El Cerrito, Califi, assignor toPrescolite Manufacturing Corporation, San Leandro, Califl, a corporationof California Filed Aug. 24, 1964, Ser. No. 391,601 8 Claims. (Cl.240-147) This invention relates to means for retaining a diffuserelement in a light fixture in such a manner that the diffuser isselectively moveable between a position in closing relation to the lighthousing of the fixture, and a second position wherein access to thehousing interior is facilitated. The invention is more particularlydirected to spring toggle retention means for the foregoing purpose.

In various light fixtures, it is desirable that the diffuser element ofthe fixture be secured to the light housing thereof in such a manner asto permit movement of the diffuser between open and closed positionsrelative to the housing while at all times retentively supporting thediffuser from the housing. More particularly, access to the interior ofthe housing, as for purposes of replacing light bulbs or other lightingelements therein, is facilitated when the diffuser is in open position.By virtue of the continuous support of the diffuser from the housingincluding times when the diffuser is in open position, the lightingelement replacement function is greatly simplified. It is not necessaryto first remove the diffuser from the fixture to afford access to theinterior of the housing. The diffuser is merely manipulated to itsretentively supported open position whereupon both hands are free forthe accomplishment of lighting element replacement.

Heretofore, the diffuser retention means employed in the continuoussupport of the diffuser during movement between closed and openpositions have been relatively complex, particularly in the instance ofa recessed fixture. In a recessed fixture the diffuser is positionedsubstantially flush with a ceiling or wall, and simple hinged attachmentof the diffuser to the housing cannot be employed because the ceiling orwall obstructs pivotal movement of the diffuser about the hinge axis.Accordingly, rather elaborate retention mechanisms have been employedwhich facilitate supported movement of the diffuser to a positionsufficiently displaced from the ceiling or wall that the diffuser maythen be unobstructively pivoted to an open position. By virtue of thecomplexity of these previous diffuser retaining mechanisms they haveadded substantially to the overall cost of the fixture.

Accordingly, it is an object of the present invention to providedifliuser retention means of relatively simple design which areparticularly suited to use in recessed lighting fixtures to facilitatecontinuously supported movement of the diffuser between closed and openpositions relative to the light housing thereof.

Another object of the. invention is the provision of retention means ofthe class described in the form of a spring toggle effective in oneposition to retain a diffuser in closed relation to a light housingwhile being resiliently yieldable to a second position wherein thediffuser is supported in displaced relation to the housing and may bepivoted to provide access to the housing interior.

Yet another object of the invention is the provision of a spring togglediffuser retention mechansm of the class described which is applicableto fixtures having light housings of either circular or rectangularcross section.

It is still another object of the invention to provide diffuserretention mechanism of the character outlined hereinbefore which isadjustable to accommodate ceilings of different thicknesses.

A further object of the invention is the provision of a 3,328,579Patented June 27, 1967 "ice . diffuser retention mechanism of the classdescribed which while being of extremely low cost design is yet highlyeffective in accomplishing its intended diffuser retention and supportfunctions.

The invention possesses other objects and features of advantage, some ofwhich, with the foregoing, will be set forth in the followingdescription of the preferred form of the invention which is illustratedin the drawings accompanying and forming part of the specification. Itis to be understood, however, that variations in the showing made by thesaid drawings and description may be adopted within the scope of theinvention as set forth in the claims.

FIGURE 1 is an elevational view with portions broken away of a lightingfixture having a light housing of circular cross section mounted inrecessed relation to a ceiling and embodying spring toggle diffuserretention mechanism in accordance with the present invention, thediffuser of the fixture being depicted in closed position relative tothe light housing.

FIGURE 2 is a fragmentary view similar to FIGURE 1, but depicting thediffuser supported in displaced position relative to the light housingby the retention mecha- IllSIl'l.

FIGURE 3 is a sectional view of the fixture taken in a diametric planerotated degrees with respect to the section plane of FIGURE 1, anddepicting the diffuser in pivoted open position.

FIGURE 4 is an elevational view with portions brokenaway of a recessedlighting fixture having a light housing of rectangular cross section andembodying a somewhat modified form of spring toggle diffuser retentionmechanism in accordance with the invention, the diffuser of the fixturebeing depicted in closed position relative to the light housing.

FIGURE 5 is a fragmentary view similar to FIGURE 4, but depicting theretention mechanism supporting the diffuser in displaced positionrelative to the light housmg.

FIGURE 6 is an elevational view of the fixture, with portions brokenaway, taken in a plane rotated 90 degrees with respect to that of FIGURE4, and depicting the diffuser in pivoted open position. I

FIGURE 7 is a fragmentary exploded perspective view of another modifiedform of the spring toggle retention mechanism.

FIGURE 8 is a fragmentary elevation view depicting still anothermodification of the spring toggle mechanism.-

Referring now to FIGURE 1, there will be seen to be provided a lightingfixture 11 which in the present in; stance includes a light housing 12of circular cross section,;

closed at one end and open at the other. A support flange 13projectsoutwardly from the housing adjacent its open end to engage theupper surface of a ceiling 14, or other wall, about an opening 16provided therein. The flangethus supports the housing in recessedposition relative to the ceiling and only a small portion adjacent theopen end of the housing extends into the opening. A socket 17 isprovided within the housing at the closed end thereof for threadablyreceiving an incandescent light bulb 18, and a junction box 19 ismounted upon the closed end of the housing to facilitate electricalwiring of the socket. More than one bulb, or lighting elements of othertypes such as fluorescent tubes, may of course be similarly mountedwithin the housing. In any event, with the housing moiinted in recessedposition relative to the ceiling, it will be appreciated that access tothe housing interior for purposes of replacing the bulb 18, or otherlighting elements, is only provided through the open lower end of thehousing.

The open lower end of the light housing of a recessed lighting fixturesuch as fixture 11 is conventionally closed by a diffuser element 21. Tofacilitate mounting of the diffuser there is typically provided amounting ring 22 having inwardly and outwardly projecting annularflanges 23 and 24 adjacent its lower end. The diffuser is provided withan outwardly flared annular flange 26 which is secured upon the inwardlyprojecting flange 23 of the mounting ring. The mounting ring may bepositioned with its upper end concentrically within the open lower endof the housing 12, at which time the diffuser closes the housing and theoutwardly projecting flange 24 of the ring flushly engages the ceilingabout opening 16. As a result the light housing and opening are neatlyobscured from view.

In accordance with the particularly salient aspects of the presentinvention, retention of the diffuser element, 21 in the above-notedclosing relation to the open end of the light housing 12 is facilitatedby means of a spring toggle retaining mechanism of unique design. Unlikeprevious rather elaborate diffuser retention arrangements, the springtoggle retention mechanism is extremely simple and yet very effectivelyperforms the desired function of retaining the diffuser in closingrelation to the open end of the light housing while providing forsupported movement of the diffuser to a position displaced from thehousing wherein the diffuser may be pivoted to permit access to thehousing interior. More particularly, the spring toggle retentionmechanism generally includes a pair of brackets respectively having oneend pivotally connected at opposed points of the interior of the housingfor movement about substantially tangential axes. In some applications,the brackets may be substantially planar. However, in the present case,the free ends of the brackets are preferably provided with angularlydirected portions 28 which project inwardly when the brackets are indownwardly pivoted positions of engagement with the housing interiorsubjacent the pivot axes of the brackets, as best shown in FIGURE 2.Resilient strip members 29 are connected between the free ends of thebrackets and the diffuser. In this regard the connecting points 31 ofthe resilient members to the brackets are inwardly spaced from theirconnecting points 32 to the diffuser when the brackets are in theirdownwardly pivoted positions. In addition, the connections 32 betweenthe resilient members and the diffuser are pivotal. Thus, in response tothe application of upward force to the diffuser, the force istransmitted through the resilient members to the brackets and operatesto pivot same upwardly. As the brackets pivot, the resilient members areinitially flexed inwardly and therefore resiliently exert outwardlydirected restoring forces upon the free ends of the brackets. Finally,at some point in the upward pivotal movements of the brackets, i.e.,beyond theirdead center positions, the restoring forces areappropriately directed with respect to the brackets to hold same inupwardly pivoted equilibrium positions as depicted in FIGURE 1. In theseequilibrium positions of the brackets, the diffuser is resilientlyretained in closing relation t2 the lamp housing. Downward force appliedto the diffuser opposes the resilient retaining forces of the resilientmembers andis effective to pivot the brackets downwardly. At some pointin the downward pivotal movements of the brackets, again beyond theirdead center positions, the resilient forces exerted by the resilientmembers upon the brackets are appropriately directed to aid the downwardpivotal movement. The brackets thereafter assume their downwardlypivoted positions of engagement with the interior of the lamp housing,at which time the resilient members depend from the brackets. Thebrackets and resilient members thus suspend the diffuser from the lamphousing in a downwardly displaced position relative thereto, andtherefore to the ceiling 14 in which the housing is recessed. In thisdownwardly displaced position, the diffuser may be pivoted with respectto the resilient members, away 4 from the housing, as indicated inFIGURE 3, to thereby permit access to its interior.

Considering now the spring toggle retention mechanism in greater detailas to the structural form thereof depicted in the embodiment of FIGURES13, it is to be first noted that the angularly directed portion 28 ofeach. bracket 27 is rightangularly directed with respect to theremainder of the bracket. In addition, each bracket is preferably of'U-shaped configuration, the end portion containing the web being bentat right angles to a plane through the parallel side legs of the bracketto thereby define the angularly directed portion 28. The ends of theside legs are bent right angularly outward in the plane of the side legsto define pivot pins 33. The pins are rotatably received in opposedtangential channels 34 formed in the peripheral wall of the lighthousing. Preferably a plurality of sets of the channels 34 are providedat longitudinally spaced positions of the housing to facilitateadjustability of the fixture to ceilings of varied thickness, as will besubsequently explained.

The resilient strip members 29 are preferably in the form of flat leafsprings. End attachment of the leaf springs to the U-shaped brackets 27is then accomplished as by means of hinge clips 36 extending around thewebs of the brackets into juxtaposition with the opposite sides of thesprings and secured thereto as by means of rivets 37. The opposite endsof the leaf springs are pivotally connected to diametrically opposedpoints of the diffuser mounting ring as by means of rivets 38.

With the spring toggle retention means provided in the form justdescribed and the housing mounted in recessed position with respect tothe ceiling 14, the pivot pins 33 of the brackets 27 are inserted in oneof the sets of channels 34. In this regard, the set of channels selectedis that for which the flange 24 of the diffuser mounting ring engagesthe ceiling when the brackets are in upwardly pivoted position. In theillustrated case the uppermost set of channels receive the pins, howeverif the ceiling were thicker a lower set of the channels would beemployed. In this regard, tht U-sh-aped brackets are sufficientlyresilient that the side legs thereof may be depressed to retract thepins from one set of channels. With the side legs still depressed,'thebrackets may be positioned with the pins opposite another set of thechannels, and the side legs then released to permit them to resilientlyspring outward to engage the pins in the channels. With the springtoggle retention mechanism thus adjusted to the particular thickness ofthe ceiling 14, operation of the mechanism is in the manner previouslydescribed. To gain access to the housing interior, the diffuser mountingring is merely pulled downward and pivoted away from the housing to theposition illustrated in FIGURE 3. To reposition the mounting ring inengagement with the ceiling and the diffuser in closing relation to thehousing, the mounting ring is merely urged upward, whereupon the springtoggle mechanism resiliently retains the ring and diffuser in suchpositions.

Referring now to FIGURES 46, a slightly modified form of the, springtoggle diffuser retention mechanism is illustrated as being applied to alight fixture wherein the light housing is of rectangular cross section.In the instant embodiment like primed numerals are employed to refer toelements which are similar to those of the embodiment of FIGURES 1-3.More particularly, the fixtu-re 11' includesa rectangular light housing12" having a rectangular base plate 39 which extends outwardly beyondthe side walls of the housing to thereby define an outwardly flaredrectangular support flange 13'. The base plate is provided with acentral opening 41 circumscribed by a depending flange 42. The flange 42is arranged to extend through an opening 16' of a ceiling 14' with theflange 13' engaging the upper surface of the ceiling to support thehousing in recessed position. Although the opening 41, flange42,and-ceiling opening 16 are illustrated as being circular, they may ofcourse be of other configurations such as rectangular. The housing 12'is equipped with a socket 17 for receiving a light bulb 18', and ajunction box 19 which in the present instance is mounted upon one sidewall of the housing.

The fixture 11' further includes a diffuser 21 secured within amountingring 22' having inwardly and outwardly flared annular flanges 23 and 24,the former supporting the diffuser and the latter being adapted toengage the ceiling 14' about opening 16'. The assembly of mounting ringand diffuser is secured to the housing 12' by a spring toggle retentionmechanism which is generally similar to that employed in the embodimentof FIGURES 1-3. More particularly, the retention mechanism includesU-shaped brackets 27' having angularly directed portions 28 at the webends thereof and pivot pins 33' at the ends of the parallel side legsthereof. In the present embodiment the portions 28 are at obtuse anglesto the side legs of the bracket rather than at right angles thereto, asin the case of the previously described embodiment. Leaf springs 29 aresecured to the webs of the brackets by means of hinge clips 36' andrivets 37'. These leaf springs are pivotally connected to diametricallyopposed points of mounting ring 22' by means of rivets 38'. Thus, itwill be appreciatedthat except for the angular orientations of bracketportions 28', the toggle mechanism is the same as that employed ni thepreviously described embodiment. One significant departure from theprevious embodiment resides, however, in the means employed tofacilitate pivotal connection of the. brackets 28 to the housing 12' atvaried longitudinal positions of accommodation toceilings of differentthickness. More particularly, in the embodiment of FIGURES 4-6,longitudinally extending channels 43 are secured to the inner wall offlange 42 at diametrically opposed positions thereof. The parallel sidelegs of the channel project inwardly into the opening 41, and sets ofaligned.- apertures 44 are provided through the side legs atlongitudinally spaced position. These apertures serve to receive thepivot pins 33 of the brackets, and adjustment of the toggle mechanism toceilings of different thickness is thus facilitated by the selection ofan appropriate set of apertures to receive the pins. With the bracketsonce pivotally mounted in a set of the channel apertures, operation ofthe spring toggle mechanism to move the mounting ring 22' and diffuser21' between the closed and open positions depicted in FIGURES 4 and 6,is the same as that previously described with respect to the embodimentof FIGURES 1-3.

Various departures from the specific spring toggle arrangements andfixture structures described hereinbefore are of course possible. Inthis regard, the leaf springs 29 (or 29) may be connected to thebrackets 27 (or 27') in the manner depicted in FIGURE 7, rather than bymeans of the hinge clips 36 (or 36). More particularly, each leaf spring29 may be formed with a tab 46 projecting longitudinally from the endthereof which is to be secured to the bracket. A clip 47 including aplanar portion 48 and arcuate portion 49 curving substantially rightangularly away from the planar portion and then returning through theplane of the portion 48 in spaced relation thereto, may then be employedto facilitate connection between the spring and bracket, In this regard,the arcuate portion of the clip is provided with a slot 51 for receivingthe spring tab 46 and the planar portion and spring are provided withregistering apertures for receiving a rivet 52, or equivalent fastener.The planar portion of the clip and the spring are thus juxtaposed andsecured together by means of the rivet 52, with the areaate portion 49extending about the web of the bracket and the tab 46 engaging the slot51.

Although the fixtures 11, 11' described hereinbefore include diffusermounting frames, such as the mounting rings 22, 22', with the springtoggle retention mechanism secured thereto, under some circumstancesmounting frames are not provided and it is then necessary that thespring toggle retention mechanism be secured directly to the diffuser.This is preferably accomplished as illustrated in FIGURE 8, wherein thespring toggle mechanism is employed in connection with a diffuser globe53 of a type having a lower wall 54 and upstanding marginal side wall 56terminating in an upper wall 57 extending inwardly to a neck 58circumscribing a central opening. Securance of the spring togglemechanism to the globe 53 is facilitated by means of a spring clip 59pivotally secured to each leaf spring 29 of the toggle and extendingabout the neck 58 outwardly into resilient engagement with the undersideof the upper wall 57. The clip 59 is of resilient material and includesa planar leg portion 61 for pivotal connection to the leaf spring 29 asby means of a rivet 62. A foot portion 63 extends right angularly fromthe leg portion and terminates in a loop portion 64 curving away fromthe foot portion and recurving to a position subjacent same. The footportion of the clip is adapted to en? gage the top surface of upper Wall57 adjacent the neck 58, while the loop portion 64 is adapted to extendover 7 the neck and through the opening of the globe, the free end ofthe loop portion then extending outwardly to resiliently engage theunderside of the wall 57. It will be appreciated that with such aconfiguration of clip 59, the gripping force exerted by the clip uponthe globe increases during movement thereof between closed and openpositions. More particularly, the direction of spring loading of theclip due to the spring 29 being inwardly flexed at its upper end duringmovement of the diffuser globe between closed and open positions is suchas to urge the clip into tighter engagement with the globe. In thismanner, there is no danger of the globe being released during itsmovement.

What is claimed is:

1. A light fixture comprising a light housing having an open end, adiffuser adapted for closing relation to said open end, a pair ofbrackets respectively having one end pivotally connected at opposedpoints of the interior of said housing adjacent said open end, and apair of resilient strip members respectively secured to the free ends ofsaid brackets and pivotally coupled to said diffuser for retaining saidbrackets in first equilibrium positions wherein said difi'user isdisposed adjacent the open end of said housingin closing relationthereto and second equilibrium positions wherein said diffuser isdisplaced from said open end, said brackets being pivotal between saidfirst and second equilibrium positions against the resilient forces ofsaid strip members beyond dead center positions of said strip memberswhereat the direction of said forces reverse,

said brackets having pivot pins and means for journalling said pins at aplurality of selective longitudinally spaced positions of said housing.

2. A light fixture comprising a light housing having an open end,diffuser mounting means disposed adjacent the open end of said housing,a pair of U-shaped brackets each having outwardly turned pin portions atthe ends of the side legs thereof in the plane of said side legs, saidbrackets each having a Web end portion angularly di rected from theplane of said side legs, means carried by said housing for journallingthe pins of said brackets respectively at opposed points of the interiorof said housing adjacent the open end thereof, said angularly directedweb end portions of said brackets projecting inwardly when the side legsthereof are disposed in parallel adjacent relation to portions of thehousing between the open end thereof and the pivot points of thebrackets, and a pair of leaf springs respectively secured at one end tothe webs of said brackets and pivotally connected at the other end tosaid diffuser mounting means.

3. A light fixture according to claim 2, wherein said means forjournalling the pins of said brackets comprise one of a plurality oflongitudinally spaced apart sets of opposed channels formed in theperipheral wall of said housing at each of a pair of opposed portionsthereof.

4, A light fixture accordingto claim 2, wherein said means forjournalling the pins of said brackets comprise a pairof longitudinallyoriented channel members secured at opposed points of the interior wallof said housing in inwardly facing relation, the side legs of eachchannel member having a plurality of longitudinally spaced aligned setsof apertures, said pins of the respective brackets en-, gaging one ofsaid sets of apertures of said channel members.

5. A light fixture comprising a cylindrical light housing having aclosed end and an open end, said housing having a plurality of sets ofopposed substantially tangential channels at longitudinally spacedpositions of each of a pair of diametrically opposed interior wallportions of the housing adjacent the open end thereof, a pair of U-shaped brackets each having outwardly turned pin portions at the ends ofthe side legs thereof in the plane of said side legs, said brackets eachhaving a web end portion directed at right angles to the plane of saidside legs, said pins of the respective brackets rotatably disposed incorresponding ones of said sets of channels at said opposed interiorwall portions of said housing, said web end portions of said bracketsprojecting inwardly when the side legs thereof are disposed in paralleladjacent relation to portions of the housing between the open endthereof and said channels, a pair of leaf springs respectively securedat one end to the webs of said brackets, a diffuser mounting ring, saidsprings pivotally connected at their free ends to diametrically opposedpoints of said ring, and a diffuser secured within said ring.

6. A light fixture comprising a rectangular light housing closed at oneend and having a base plate at the other end with a central openingcircumscribed by a lon-- gitudinally outwardly projecting flange, a pairof longitudinal channel members secured at opposed points of the innerperiphery of said flange in inwardly facing relation, the side legs ofeach channel member having a plurality of longitudinally spaced alignedsets of apertures, a pair of U-shaped-brackets each having outwardlyturned pin portions at the ends of the side legs thereof in the plane ofsaid side legs, said brackets each having a Web'end portion directed atan obtuse angle to the planetof said side legs, said pins of therespective brackets rotatably disposed in corresponding ones of saidsets of apertures of said channel members, said Web end portions of saidbrackets projecting inwardly when the side legs thereof are disposed inparallel adjacent relationto portions of said channel members betweenthe outer ends thereof and ends to'opposed points of said frame, and adifiuser secured within said. frame.

7. A light fixture comprising a light housing having an open end, ad'fiuser adapted forclosing relation to said open end, a pair ofU-shaped brackets pivotally connected at their free ends to opposedpoints of the interiorof said housing adjacent said open end, a pair ofleaf springs each having a tab projecting longitudinally from one endthereof, and a pair of clips, said clips each includinga planar portionand an arcuate portion curving substantially right angularly away fromthe planar portion and then returning through the plane of the planarportion in spaced relation thereto, said arcuate portion having a slottherethrough, said clips respectively-having their planar portionssecured to said leaf springs and their arcuate portions extending aboutthe Webs of said brackets with said tabs engaging said slots, said leafsprings having their free ends pivotally coupled to said diffuser.

8. A light fixture comprising a light housing having an open end, adiffuser globe adapted for closing relation to, said open end, saidglobe having a lower wall and upsaid apertures, a pair of leaf springsrespectively secured at one end to the webs of said brackets, a diffusermounting frame, said springs pivotally connected at their free standingmarginal side wall terminating in an upper wall extending inwardly to aneck circumscribing a central opening, a pair of brackets respectivelyhaving one end pivotally connected at opposed points of the interior ofsaid housing adjacent said open end thereof, said brackets havingangularly inwardly directed free ends, a pair of leaf springsrespectively secured tothe free ends of said brackets, and a pair ofspring clips each including a planar leg portion and foot portionextending right angularly from the leg portion terminating in a loopportion curving away from the foot portion and recurving to a positionsubjacent same, said clips respectively having their leg portionspivotally secured to the free ends of said springs and their footportions engaging the top surface of said upper wall of said globeadjacent the neck thereof, said loop portions of said clips extendingover said neck and through the opening of said globe outwardly intoengagement with the bottom surface of said upper wall.

References Cited UNITED STATES PATENTS 2,806,726 9/1957 Broberg 240-146XR 2,826,684 3/1958 Baker 240-147 XR' 3,029,335 4/1962 Jones 240-1473,052,372 9/1962 Shepherd 240-147 3,099,404 7/ 1963 Kraufman et a1.240--147 XR 3,142,447 7/1964 Bodian 240-147 NORTON ANSHER, PrimaryExaminer.

C. C. LOGAN, Assistant Examiner.

1. A LIGHT FIXTURE COMPRISING A LIGHT HOUSING HAVING AN OPEN END, ADIFFUSER ADAPTED FOR CLOSING RELATION TO SAID OPEN END, A PAIR OFBRACKETS RESPECTIVELY HAVING ONE END PIVOTALLY CONNECTED AT OPPOSEDPOINTS OF THE INTERIOR OF SAID HOUSING ADJACENT SAID OPEN END, AND APAIR OF RESILIENT STRIP MEMBERS RESPECTIVELY SECURED TO THE FREE ENDS OFSAID BRACKETS AND PIVOTALLY COUPLED TO SAID DIFFUSER FOR RETAINING SAIDBRACKETS IN FIRST EQUILIBRIUM POSITIONS WHEREIN SAID DIFFUSER ISDISPOSED ADJACENT THE OPEN END OF SAID HOUSING IN CLOSING RELATIONTHERETO AND SECOND EQUILIBRIUM POSITIONS WHEREIN SAID DIFFUSER ISDISPLACED FROM SAID OPEN END, SAID BRACKETS BEING PIVOTAL BETWEEN SAIDFIRST AND SECOND EQUILIBRIUM POSITIONS AGAINST THE RESILIENT FORCES OFSAID STRIP MEMBERS BEYOND DEAD CENTER POSITIONS OF SAID STRIP MEMBERSWHEREAST THE DIRECTION OF SAID FORCES REVERSE, SAID BRACKETS HAVINGPIVOT PINS AND MEANS FOR JOURNALLING SAID PINS AT A PLURALITY OFSELECTIVE LONGITUDINALLY SPACED POSITIONS OF SAID HOUSING.